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HVPE GaN (hvpe + gan)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Bulk growth of gallium nitride: challenges and difficulties

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007
M. Bockowski
Abstract The present status of the GaN bulk growth by High Pressure Solution (HPS) method and combination of HPS and Hydride Vapor Phase Epitaxy (HVPE) methods is reviewed. Up to now the spontaneous high pressure solution growth of GaN results in crystals having habit of hexagonal platelets of surface area of 3 cm2 or needles with length up to 1 cm. Recently, the platelets and needles have been used as seeds for the HVPE growth. On the other hand, the LPE technique under pressure with pressure-grown GaN (hp-GaN), GaN/sapphire template, patterned GaN/sapphire template and free standing HVPE GaN as seeds has been examined and developed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The nucleation of HCl and Cl2 -based HVPE GaN on mis-oriented sapphire substrates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010
Tim Bohnen
Abstract The nucleation of both classic HCl-based and novel Cl based HVPE GaN on mis-oriented sapphire substrates was investigated. The use of Cl2in HVPE increases the growth rate by a factor of 4-5 and strongly reduces the parasitic deposition, allowing for the growth of much thicker wafers than HCl-based HVPE. Morphological SEM surface studies of the HCl-based HVPE sample surface show that at 600 °C a nanocrystalline layer is deposited on the sapphire. During the subsequent annealing phase, the morphology changes to a ,m-sized island structure. During overgrowth at 1080 °C, the islands coalesce. Small voids or pinholes are then formed in between the coalescing GaN islands. These pinholes lead to numerous pits on the surface of the GaN at thicknesses of 5 ,m. The pits disappear during continued overgrowth and can no longer be found on the surface, when the GaN film reaches a thickness of 45 ,m. This particular coalescence mechanism also applies to Cl2 -based HVPE GaN on sapphire (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Nonpolar a -plane HVPE GaN: growth and in-plane anisotropic properties

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005
T. Paskova
Abstract Nonpolar GaN thick films with [11-20] orientation were grown on [1-102] oriented sapphire by hydride vapour phase epitaxy (HVPE) utilizing reactively sputtered AlN buffers. Growth rate and microstructure of such films were investigated and compared to those in HVPE [0001] oriented GaN thick films. The structural parameters show an angular azimuth dependence implying in-plane non-homogeneity. The lattice parameters and strain components were determined by using plane and edge symmetric measurement geometries. A red shift observed in the near band edge photoluminescence is explained by the specific strain distribution studied independently by X-ray diffraction. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]